tests: add hex() in tests to avoid non-utf8 chars in result file

[Defined2014]

What problem does this PR solve?

Issue Number: ref #45961

Problem Summary: Because .result file has some non-utf8 characters, github thinks it's a binary file which inconvenient for us to review. Follow MySQL, add hex() function to avoid such problems.

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[tiprow]

Hi @Defined2014. Thanks for your PR.

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[codecov]

Codecov Report

Merging #47118 (0e5d88d) into master (d569d19) will decrease coverage by 0.3448%.
Report is 2 commits behind head on master.
The diff coverage is n/a.

❗ Current head 0e5d88d differs from pull request most recent head f571e52. Consider uploading reports for the commit f571e52 to get more accurate results

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #47118        +/-   ##
================================================
- Coverage   72.9684%   72.6236%   -0.3449%     
================================================
  Files          1338       1359        +21     
  Lines        399152     405441      +6289     
================================================
+ Hits         291255     294446      +3191     
- Misses        89082      92279      +3197     
+ Partials      18815      18716        -99     

Flag	Coverage Δ
integration	30.4506% <ø> (?)
unit	72.9684% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9913% <ø> (ø)
parser	84.9728% <ø> (ø)
br	48.5886% <ø> (-4.3396%)	⬇️

[Defined2014]

See https://github.com/Defined2014/tidb/blob/fix-binary-file/tests/integrationtest/r/expression/builtin.result, github no longer think it is a binary file.

[SeaRise]

lgtm

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: SeaRise, tiancaiamao

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-09-20 06:25:34.897328589 +0000 UTC m=+671500.864916639: ☑️ agreed by SeaRise.
• 2023-09-20 09:09:56.207446092 +0000 UTC m=+681362.175034142: ☑️ agreed by tiancaiamao.